Penalty, Sec. 976.)


Sec. 924. [=Ventilation of mines while persons working therein.=] At
each mine where the ventilation is not continuous, it shall be
started a sufficient length of time prior to the appointed time for
any person, or persons, working therein to enter, to clear the mine
of explosive, poisonous and noxious gases, and shall be kept in
operation a sufficient length of time after the appointed time for
such employes to leave their working places, for all persons to be
out of the mine. (Sec. 922, 923, 952; Penalty, Sec. 976.)


[=Pressure gauges.=] At each mine generating fire-damp so as to be
detected by a safety lamp, and wherein twenty or more persons are
employed, a recording pressure gauge for the purpose of recording
the pressure or vacuum of the main air current, shall be provided
and maintained, which shall be kept in constant use, and records
preserved for ninety days, subject to the inspection of the chief
inspector of mines and the district inspector of mines. (Penalty,
Sec. 976.)


Sec. 925. [=Competent person or persons shall be designated as
fire-boss.=] The owner, lessee or agent of a mine generating
fire-damp so as to be detected by a safety lamp, shall designate a
competent person or persons as fire boss or fire bosses, who shall
make a thorough examination of each working place in the mine every
morning with a standard safety lamp, not more than three hours prior
to the appointed time for the employes to enter the mine. As